Known marine radars offer the capability to image ocean wave propagation by virtue of repetitive coverage of the same scene. With a typical 1.25 second rotation period of a marine radar, ocean wave frequencies of 0.4 Hertz (Hz) can be measured unambiguously. Imaged areas of the order of ten square kilometers, allow the dynamics and kinematics of ocean wave fields to be measured by marine radars with higher azimuthal resolution than traditional oceanographic instruments, such as buoys or pressure sensors.
Using the dispersion relation for shallow waves in coastal regions, ocean wave spectra and bathymetry can be estimated using known non-coherent marine radars. The derivation of ocean wave height or ocean wave height spectra from marine radar imagery has had some success by relating the radar echo intensity imagery of waves to wave height using an empirically derived modulation transfer function (MTF) to scale echo intensity to wave height, as shown by U.S. Pat. No. 6,775,617, to Seemann, incorporated herein by reference. However, in coastal waters in general, or in deep waters when wind direction shifts rapidly, winds blowing in a direction other than parallel to that of the wave field can produce enhanced roughness on the front face of waves. This results in a modulation of the radar wave field image that is not wave height dependent and can create errors in wave height measurement, such as disclosed by D. Trizna and K. Hathaway, “Monitoring Coastal Processes and Ocean Wave Directional Spectra Using a Marine Radar”, Ocean Sciences 2006, Honolulu, pp. 1-2, 20-24 Feb. 2006.